Diffusion-weighted imaging in rectal carcinoma patients without and after chemoradiotherapy: a comparative study with histology.

Diffusion-weighted imaging (DWI) can be used to quantitatively assess functional parameters in rectal carcinoma that are relevant for prognosis and treatment response assessment. However, there is no consensus on the histopathological background underlying the findings derived from DWI. The aim of this study was to perform a comparison of DWI and histologic parameters in two groups of rectal carcinoma patients without (n=12) and after (n=9) neoadjuvant chemoradiotherapy (CRT). The intravoxel incoherent motion (IVIM) model was used to calculate the diffusion coefficient D and the perfusion fraction f in rectal carcinoma, the adjacent rectum and fat in the two patient groups. Immunohistological analysis was performed to assess the cellularity, vascular area fraction and vessel diameter for comparison and correlation. Out of 36 correlations between parameters from DWI and histology, four were found to be significant. In rectal carcinoma of patients without CRT, the diffusion D and the perfusion f correlated with the vascular area fraction, respectively, which could not be found in the group of patients who received CRT. Further correlations were found for the rectum and fat. Histological evaluation revealed significant differences between the tissues on the microscopic level concerning the cellular and vascular environment that influence diffusion and perfusion. In conclusion, DWI produces valuable biomarkers for diffusion and perfusion in rectal carcinoma and adjacent tissues that are highly dependent of the underlying cellular microenvironment influenced by structural and functional changes as well as the administered treatment, and consequently can be beyond histological ascertainability.

MITK diffusion imaging.

BACKGROUND: Diffusion-MRI provides a unique window on brain anatomy and insights into aspects of tissue structure in living humans that could not be studied previously. There is a major effort in this rapidly evolving field of research to develop the algorithmic tools necessary to cope with the complexity of the datasets. OBJECTIVES: This work illustrates our strategy that encompasses the development of a modularized and open software tool for data processing, visualization and interactive exploration in diffusion imaging research and aims at reinforcing sustainable evaluation and progress in the field. METHODS: In this paper, the usability and capabilities of a new application and toolkit component of the Medical Imaging and Interaction Toolkit (MITK, www.mitk.org), MITK-DI, are demonstrated using in-vivo datasets. RESULTS: MITK-DI provides a comprehensive software framework for high-performance data processing, analysis and interactive data exploration, which is designed in a modular, extensible fashion (using CTK) and in adherence to widely accepted coding standards (e.g. ITK, VTK). MITK-DI is available both as an open source software development toolkit and as a ready-to-use installable application. CONCLUSIONS: The open source release of the modular MITK-DI tools will increase verifiability and comparability within the research community and will also be an important step towards bringing many of the current techniques towards clinical application.

[Introduction to the basic principles and techniques of diffusion-weighted imaging]. / Einführung in die Grundlagen und Techniken der Diffusionsbildgebung.

This article gives an overview of the many different technical aspects of diffusion-weighted imaging and a review of the physical and mathematical background. Specific terms, such as free and restricted diffusion are introduced and elucidated. The measurement of diffusion by magnetic resonance imaging (MRI) and which phenomena can occur are described. Finally, an overview of current developments in diffusion imaging and its application in research is presented.

The extensible open-source rigid and affine image registration module of the Medical Imaging Interaction Toolkit (MITK).

Although non-rigid registration methods are available or under development for many specific problems in medicine, rigid and affine registration is an important task that is often performed for pre-aligning images before using non-rigid registration. In this paper, we present a free and open-source application for rigid and affine image registration, which is designed both for developers and for end-users. The application is based on the Medical Imaging Interaction Toolkit (MITK) and allows for inter-modality and intra-modality rigid 2D-2D and 3D-3D registration of medical images such as CT, MRI, or ultrasound. The framework as well as the application can be easily extended by adding new transforms, metrics and optimizers. Thus, developers of new algorithms are enabled to test and use their algorithms more quickly, spending less work on user interfaces. Additionally, the framework provides the possibility to use image masks to restrict the evaluation of metric values by the optimizer on certain areas of the images.